This invention relates to an apparatus utilizing charged particles and more particularly, to an ion implantation apparatus used for producing semiconductor electronic circuits.
FIG. 1 is a partially sectioned schematic view showing an area around a semiconductor substrate in a conventional ion implantation apparatus. In this figure, a substrate 1 such as a semiconductor substrate which is to be ion-implantated is disposed on the wall of a vacuum chamber 2. Gas in the vacuum chamber 2 is exhausted to the extent that the scattering of an ion beam 3 is negligible by using a vacuum pump 4 provided on one side of the vacuum chamber 2. The ion beam 3 is generated by an ion beam generator (not shown), and then irradiated into the vacuum chamber 2 through an opening 2a thereof to implant ions into the substrate 1.
With the conventional apparatus utilizing charged particles constructed in the above manner, when an insulating material such as a photo-resist is formed on the surface of the substrate 1, the charge caused by the incidence of the ion beam 3 accumulates to generate a high electrical field around the insulating material. Therefore, there arises the problem that the high electrical field generated will destroy an electrical circuit formed on the semiconductor substrate 1.